菜蚜茧蜂对六种杀虫剂抗药性的季节性变化

采用药膜法研究了福州建新和闽侯上街菜蚜茧蜂Diaeretiella rapae对杀虫剂抗药性的季节性变化。田间菜蚜茧蜂种群在网室内脱离选择压力后对杀虫剂敏感性显著升高。与敏感的F₂₁子代的LC₅₀相比，2002年6月8日至2004年11月18日期间，建新菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为11.8～31.2，9.3～14.7，9.3～35.7，7.0～16.6，和13.3～30.1倍；2003年6月5日至2004年12月17日期间，上街菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为7.5～34.9，4.0～14.3，9.2～38.6，7.8～18.9和12.1～24.2倍。田间菜蚜茧蜂种群在5月份和6月初抗性水平最高，12月份较低，6月末最低，尤其在6月份期间20天内抗性水平急剧下降。研究结果表明，田间菜蚜茧蜂对6种杀虫剂的抗性水平在脱离选择压力后不稳定，且呈显著的季节性变化。表2参25

Seasonal dynamics of resistance to six insecticides in the field populations of parasitoid Diaeretiella rapae(M' Intosh) (Hymenoptera: Aphidiidae)

The resistance to six insecticides in the field populations of Diaeretiella rapae (Hymenoptera: Aphidiidae),a parasitoid of vegetable aphid collected in Jianxin, Fuzhou City, and Shangjie, Minhou County, Fujian, China, was studied using dry residual film method. The susceptibility to insecticides in a field population of D. rapae increased significantly after being reared in the field insectarium under insecticide-free conditions. Compared to susceptible F21 reared in the insectarium, the resistance ratios were 11.8-31.2 for methamidophos, 9.3-14.7 for fipronil, 9.3-35.7 for avermectin, 7.0-16.6 for fenvalerate and 13.3-30.1 for imidacloprid, respectively in Shangjie populations during June 8, 2002 to November 18, 2004; and 7.5-34.9 for methamidophos, 4.0-14.3 for fipronil, 9.2-38.6 for avermectin, 7.8-18.9 for fenvalerate and 12.1-24.2 for imidacloprid, respectively in Shangjie populations during June 5, 2003 to December 17, 2004. RR in field populations of D. rapae was the highest in May, early June and November, lower in December, and the lowest in the end of June. In particular, RR decreased markedly in about 20 days from the beginning to the end in June. The results indicated that the resistance levels to methamidosphos, fipronil, avermectin, fenvalerate, cypermethrin and imidacloprid in D. rapae were not stable after relaxation from the selection pressure of insecticide, and that there existed significantly seasonal variations of resistance levels to the six insecticides in D. rapae.